"In this fascinating and accessible book, Leo J. Blanken blends game theory and historical analysis with economic, legal, and conflict theories to explain long-recognized puzzles in the history of imperialism. Rational Empires is both a good read and a major analytical work that will be of interest to those who study imperialism, property rights, institutions, and conflict."

--Scott Sigmund Gartner, Pennsylvania State University

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"Imperialism" is an evocative word. It summons images of grim Roman legions marching through German forests, Maxim machine guns cutting down hordes of Dervishes at Omdurman, or scenes of torture from the classic French film "Battle of Algiers." These images share two attributes: they are noxious and they are historical - as Tennyson might describe them, "portions and parcels of the dreadful past." But is this, indeed, the case? Might imperialism have a future? To answer this question, the first task must be an examination of past strategies of imperialism. The second task is to show the contending schools of thought regarding imperialism's demise. Did the strategy of imperialism end as a rational cost-benefit calculation, based on changing military technology and economic opportunities? Or has it evolved into a socially constructed taboo, based on developing norms that deem the imperial enterprise to be abhorrent? These two approaches - economistic calculation ("rational choice") versus sociologically formed norms of acceptable behavior ("constructivism") - are often seen as irreconcilable schools of thought in international relations theory, and yet both seem crucial to understanding imperialism. In Rational Empires, for example, I develop a rationalist choice model to explain the decline of imperial activity, and yet serious questions remain as to how such analyses contend with, and might contribute to, the development of norms, values, and taboos. Finally, it is important to think about the future. If we do understand how imperialism declined, under what conditions may it again arise?

The imperial enterprise - the large-scale subjugation of foreign peoples through the use of force - is commonly treated as an artifact of a bygone age. In fact, the words "imperialism" or "empire" remain in the contemporary political discourse as pejorative terms for military interventions, the transnational activities of major corporations, and sometimes are even applied to the cultural global pandemics of Starbucks, Justin Bieber, and Facebook. The fact that the term has been stretched to include these disparate phenomena underlines the point that the original use of the term - to describe the violent colonization of massive swaths of territory and population - has essentially been retired. It would be just as bizarre for Barack Obama to announce that the US would formally colonize Haiti as it would be to announce that their people would be enslaved; both of these policies are now seen as repugnant anachronisms.

If formal imperialism had indeed passed away, then this would be one of the most fundamental changes in the history of international relations. Human societies had always been organized, and periodically reorganized, through the use of force. Since the beginning of settled agricultural communities, extending back to the walled city of Jericho in the ninth millennium BC, and extending through such vast empires as the Han, the Roman, the Mongol, and the Victorian, the imperial enterprise has defined the political landscape of the globe. Why would this no longer be the case?

First, it is necessary to define the phenomenon of formal imperialism. I have found that the most useful way is to analyze imperialism along two dimensions. The first dimension is obvious; does a powerful actor engage in grabbing territory from weak actors in the international system or not? A second dimension is the degree to which such imperial actors cooperate, or come into conflict with one another, while in the act of such territorial acquisitions. When we consider both of these dimensions together, we can explore interesting variation that has often been neglected in the analysis of the subject; we can explain both the conditions under which colonies are seized and how such activity may or may not spark wider conflict in the international system.

Based on this conceptualization of imperialism, it seems that at least three distinct patterns of imperial behavior have been in equilibrium at various times in history. The first pattern is what I term "pugnacious imperialism", in which powerful actors grab territory and clash with one another over such territory. This has characterized most of history. The French and British conflict during the Seven Years War is one stark example, in which bitter war over colonial territory raged from the forests of North America to the spice trading ports of South Asia. Another outcome might be termed "courteous imperialism", in which imperial powers peacefully divide territory among themselves. In this case, it is important to note, that "courtesy" exists solely among the imperial powers, and is not extended to the actual targets of imperialism - who may suffer considerably during the process. This occurred during the remarkable "scramble for Africa" in the last quarter of the nineteenth century, in which the majority of that continent was placidly divided among the European powers over tea and biscuits. Finally, a third equilibrium outcome may be considered, a "refraining equilibrium" in which powerful actors mutually abstain from imperial activity altogether. This has characterized the system in the decades since the Second World War, in which massive waves of decolonization have taken place and extremely fragile polities have been allowed to survive without fear of imperial predation. This is truly a novel state of affairs in the anarchic international system. Too often, however, theories of imperialism have focused on the spread of imperialism throughout history while ignoring its precipitous decline over the last century.

In Rational Empires, I argue that the incentives provided by domestic political institutions within the imperial power explain a great deal of the global dynamics of imperialism. Further, I argue that the political institutions within rival imperial powers, as well as within the potential targets of imperialism allow the leaders to craft their strategic choices. I argue that states with less democratic domestic political institutions will have a pressing need to acquire additional resources, due to the rent-seeking behavior endemic to such political systems. I show that this results in a dominant strategy of imperial expansion. This helps explain why empires like Castilian Spain expanded to the point of collapse, or why the moribund Portuguese empire clung to its African possessions through the 1970s, long after other nations had decolonized. On the other hand, states with more democratic political institutions only take territory under specified conditions, namely to reduce uncertainty when the target territories do not have attractive institutions for economic penetration. This is analogous to an automobile corporation that may purchase an upstream supplier, such as a tire company - what is referred to in economics as "vertical integration."

The theory, then, helps to account for the three equilibria described above, through the proliferation of political institutions around the globe. It accords with the long periods of "pugnacious imperialism," when there were autocratic imperial powers and a dearth of robust state structures in the lesser developed regions of the world. It also accords with the "courteous imperialism" of the nineteenth century, as liberal empires peacefully crafted policy to gain mutual access to Africa and China. Finally, it helps explain the modal outcome of "refraining" from imperialism in recent decades, as European-style state structures have proliferated around the world along with the near dominance of democracy among the world's powerful actors.

What I present in Rational Empires is a rational choice model of imperial activity that relies on some core assumptions, including the need for leaders to generate state revenue through their policy. Many would argue that this is not the best way to explain the dynamics of imperialism, as it imposes strong ethnocentric values (materialism) and cognitive tools (rationalism) throughout history and across disparate cultures to generate predictions. Thus, my work stands in stark contrast to much of the recent constructivist work on the subject, which eschews abstract economistic models of choice and contends that the decline of imperialism stems from an obvious cause: it has become taboo. This rival account has a strong intuitive appeal, especially as it implies that we have evolved morally as a species.

I cannot dismiss such a rival explanation, and have no desire to do so. In fact, I show in my work that, rather than being a competing explanation, the rational choice outcome that explains the decline of imperialism in my model (the "refraining equilibrium") actually helps to explain the establishment of the anti-imperial taboo. It provides an endogenously binding outcome around which such a norm could have coalesced and ossified; in other words, it identifies an outcome that is a rational response for actors and thereby fosters a change in social norms. International relations theory has been diverging widely in the last two decades, with the academy pitting rational choice and constructivist accounts against one another in ways that are not always helpful to our increased understanding. Imperialism is a particular subject matter in which, it seems to me, neither position can be discarded in any fruitful analysis. Norms matter: they constrain leaders politically and psychologically. Norms, however, also change, and constructivists have not yet succeeded in providing an internal engine for predicting normative change within their work. In the case of imperialism, rational choice arguments can, on the other hand, provide the plausible engine for normative changes.

Does imperialism have a future? This raises important questions and divergent predictions from the various arguments of imperialism. If one relies solely on constructivist arguments, there is little ability to make predictions concerning the timing and direction of normative change. The argument in Rational Empires, however, makes specific predictions regarding a nation such as China - resource poor, undemocratic, and growing rapidly - as having a dominant strategy to take territory. If US hegemony were to entirely dissipate, how long would the current norm of anti-imperialism endure? Would it outweigh the incentive for imperialism that I argue exists for autocratic leaders? Will the taboo turn out to have been simply a passing artifact of a transitory rational choice equilibrium? Former undersecretary of defense Dov Kakheim, for example, has recently noted a subtle and disturbing shift in the tenor of international discourse; he argues that many rising powers "reject the post-World War II settlement as outdated and will not automatically accept American leadership on any given issue.There is no indication that the sense of empire, and the sense of entitlement that accompanies it, is waning in any of these.countries. On the contrary, it seems to be getting stronger with each passing year." (1)

We need to continue researching these questions, and one can only hope that we will proceed with an increased sensitivity to a wide range of theoretical approaches. Only by doing so will we effectively analyze the past - and future - of imperialism.

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Leo J. Blanken is assistant professor in the Department of Defense Analysis at the Naval Postgraduate School.